say it: KOWN-tur-akt
counteract is a verb meaning "act in opposition to". It carries 4 recorded senses.
act in opposition to
oppose or check by a counteraction
oppose and mitigate the effects of by contrary actions
“This will counteract the foolish actions of my colleagues”
Forms marked · are formed by the regular rule rather than recorded in the source data. English keeps a few hundred irregulars and the rest follow the pattern, so the rule is right far more often than not — but it is a rule, and the mark says so.
Definitions, synonyms and semantic relations for counteract come from Princeton University’s WordNet. The pronunciation comes from the CMU Pronouncing Dictionary. Commonness is measured against a corpus of everyday English. Full sources and licences.